Electroluminescent materials and devices

ABSTRACT

An electroluminescent material is a metal complex of 1-phenyl-3-methyl-4-trimethylacetyl-pyrazol-5-one of formula (I). An electroluminescent device comprising the compound of formula (I) in the luminescent layer is also part of the invention.

The present invention relates to electroluminescent materials anddevices incorporating electroluminescent materials.

Materials which emit light when an electric current is passed throughthem are well known and used in a wide range of display applications.Liquid crystal devices and devices which are based on inorganicsemiconductor systems are widely used; however these suffer from thedisadvantages of high energy consumption, high cost of manufacture, lowquantum efficiency and the inability to make flat panel displays.

Organic polymers have been proposed as useful in electroluminescentdevices, but it is not possible to obtain pure colours; they areexpensive to make and have a relatively low efficiency.

Another compound which has been proposed is aluminium quinolate, butthis requires dopants to be used to obtain a range of colours and has arelatively low efficiency.

Patent application WO98/58037 describes a range of lanthanide complexeswhich can be used in electroluminescent devices which have improvedproperties and give better results. Patent Applications PCT/GB98/01773,PCT/GB99/03619, PCT/GB99/04030, PCT/GB99/04024, PCT/GB99/04028,PCT/GB00/00268 describe electroluminescent complexes, structures anddevices using rare earth chelates.

Hitherto electroluminescent metal complexes have been based on a rareearth, transition metal, lanthanide or an actinide or have beenquinolates such as aluminium quinolate.

We have now invented electroluminescent materials which do not include arare earth, transition metal, lanthanide or an actimide.

According to the invention there is provided an electroluminescentcompound which has the formula

where M is a metal other than aluminium; n is the valency of M; R₁, R₂and R₃ which may be the same or different are selected from hydrogen,hydrocarbyl groups, substituted and unsubstituted aliphatic groupssubstituted and unsubstituted aromatic, heterocyclic and polycyclic ringstructures, fluorocarbons such as trifluoryl methyl groups, halogenssuch as fluorine or thiophenyl groups or nitrile; R₁, and R₃ can also beform ring structures and R₁, R₂ and R₃ can be copolymerisable with amonomer, e.g. styrene.

The compounds of formula (I) can be coordinated with a neutral ligandsuch as L_(p) To form a complex

where Lα is of formula

where M is a metal, n is the valency of M and Lp is a neutral ligand.

The groups L_(p) can be selected from

Where each Ph which can be the same or different and can be a phenyl(OPNP) or a substituted phenyl group, other substituted or unsubstitutedaromatic group, a substituted or unsubstituted heterocyclic orpolycyclic group, a substituted or unsubstituted fused aromatic groupsuch as a naphthyl, anthracene, phenanthrene or pyrene group. Thesubstituents can be for example an alkyl, aralkyl, alkoxy, aromatic,heterocyclic, polycyclic group, halogen such as fluorine, cyano, amino.Substituted amino etc. Examples are given in FIGS. 8 and 9 of thedrawings where R, R₁, R₂, R₃ and R₄ can be the same or different and areselected from hydrogen, hydrocarbyl groups, substituted andunsubstituted aromatic, heterocyclic and polycyclic ring structures,fluorocarbons such as trifluoryl methyl groups, halogens such asfluorine or thiophenyl groups; R, R₁, R₂, R₃ and R₄ can also formsubstituted and unsubstituted fused aromatic, heterocyclic andpolycyclic ring structures and can be copolymerisable with a monomere.g. styrene. R, R₁, R₂, R₃ and R₄ can also be unsaturated alkylenegroups such as vinyl groups or groups

where R is as above.

L_(p) can also be compounds of formulae

where R₁, R₂ and R₃ are as referred to above, for example bathophenshown in FIG. 10 of the drawings in which R is as above or

where R₁, R₂ and R₃ are as referred to above.

L_(p) can also be

where Ph is as above.

Other examples of L_(p) chelates are as shown in FIG. 11 and fluoreneand fluorene derivatives e.g. a shown in FIG. 12 and compounds offormulae as shown as shown in FIGS. 13 to 15.

The invention also provides an electroluminescent device comprising (i)a first electrode, (ii) an electroluminescent layer comprising a layerof a complex of formula (I) and (iii) a second electrode.

Examples of R₁ and/or R₂ and/or R₃ include aliphatic, aromatic andheterocyclic alkoxy, aryloxy and carboxy groups, substituted andsubstituted phenyl, fluorophenyl, biphenyl, phenanthrene, anthracene,naphthyl and fluorene groups alkyl groups such as t-butyl, heterocyclicgroups such as carbazole.

Preferably R₁ and R₂ are Ph₁ and Ph₂ and at least one of Ph₁ and Ph₂ isa substituted or unsubstituted aromatic compound and the other Ph moietyis selected from hydrogen, and substituted and unsubstituted hydrocarbylgroups such as substituted and unsubstituted aliphatic groups,substituted and unsubstituted aromatic, heterocyclic and polycyclic ringstructures, fluorocarbons such as trifluoryl methyl groups, halogenssuch as fluorine; substituted and unsubstituted fused aromatic,heterocyclic and polycyclic ring structures and can be copolymerisablewith a monomer, e.g. styrene, fluorocarbons such as trifluoryl methylgroups, halogens such as fluorine. Examples include aliphatic, aromaticand heterocyclic alkoxy, aryloxy and carboxy groups, substituted andsubstituted phenyl, fluorophenyl, biphenyl, phenanthrene, anthracene,naphthyl and fluorene groups alkyl groups such as t-butyl, heterocyclicgroups such as carbazole.

Preferably R₁ is methyl and R₂ is

Preferred metals are metals other than aluminium, e.g. gallium, indium,germanium, tin (II), tin (IV), antimony (II), antimony (IV), lead (II),lead (IV) and metals of the first, second and third groups of transitionmetals in different valence states e.g. manganese, iron, ruthenium,osmium, cobalt, nickel, palladium(II), palladium(IV), platinum(II),platinum(IV), cadmium, chromium. titanium, vanadium, zirconium,tantulum, molybdenum, rhodium, iridium, titanium, niobium, scandium,yttrium, and R₃ is preferably a phenyl or substituted phenyl group.

Preferably there is a hole transmitting layer deposited on thetransparent substrate and the electroluminescent material is depositedon the hole transmitting layer. The hole transmitting layer serves totransport holes and to block the electrons, thus preventing electronsfrom moving into the electrode without recombining with holes. Therecombination of carriers therefore mainly talces place in the emitterlayer.

Hole transmitting layers are used in small molecule based polymerelectroluminescent devices and in electroluminescent devices based onrare earth metal complexes and any of the known hole transmittingmaterials in film form can be used.

Hole transmitting layers are used in polymer electroluminescent devicesand any of the known hole transmitting materials in film form can beused.

The hole transmitting layer can be made of a film of an aromatic aminecomplex such as poly(vinylcarbazole),N,N′-diphenyl-N,N′-bis(3-methylphenyl)-1,1′-biphenyl-4,4′-diamine (TPD),an unsubstituted or substituted polymer of an amino substituted aromaticcompound, a polyaniline, substituted polyanilines, polythiophenes,substituted polythiophenes, polysilanes etc. Examples of polyanilinesare polymers of

where R is in the ortho—or meta-position and is hydrogen, C1-18 alkyl,C1-6 alkoxy, amino, chloro, bromo, hydroxy or the group

where R is alky or aryl and R′ is hydrogen, C1-6 alkyl or aryl with atleast one other monomer of formula I above.

Polyanilines which can be used in the present invention have the generalformula

where p is from 1 to 10 and n is from 1 to 20, R is as defined above andX is an anion, preferably selected from Cl, Br, SO₄, BF₄, PF₆, H₂PO₃,H₂PO₄, arylsulphonate, arenedicarboxylate, polystyrenesulphonate,polyacrylate alkysulphonate, vinylsulphonate, vinylbenzene sulphonate,cellulosesulphonate, camphor sulphonates, cellulose sulphate or aperfluorinated polyanion.

Examples of arylsulphonates are p-toluenesulphonate, benzenesulphonate,9,10-anthraquinone-sulphonate and antliracenesulphonate, an example ofan arenedicarboxylate is phthalate and an example of arenecarboxylate isbenzoate.

We have found that protonated polymers of the unsubstituted orsubstituted polymer of an amino substituted aromatic compound such as apolyaniline are difficult to evaporate or cannot be evaporated; howeverwe have surprisingly found that if the unsubstituted or substitutedpolymer of an amino substituted aromatic compound is de-protonated itcan be easily evaporated i.e. the polymer is evaporable.

Preferably evaporable de-protonated polymers of unsubstituted orsubstituted polymer of an amino substituted aromatic compound are used.The de-protonated unsubstituted or substituted polymer of an aminosubstituted aromatic compound can be formed by deprotonating the polymerby treatment with an alkali such as ammonium hydroxide or an alkalimetal hydroxide such as sodium hydroxide or potassium hydroxide.

The degree of protonation can be controlled by forming a protonatedpolyaniline and de-protonating. Methods of preparing polyanilines aredescribed in the article by A. G. MacDiarmid and A. F. Epstein, FaradayDiscussions, Chem Soc. 88 P319 1989.

The conductivity of the polyaniline is dependent on the degree ofprotonation with the maximum conductivity being when the degree ofprotonation is between 40 and 60%, e.g. about 50%.

Preferably the polymer is substantially fully de-protonated.

A polyaniline can be formed of octamer units i.e. p is four, e.g.

The polyanilines can have conductivities of the order of 1×10⁻¹ Siemencm⁻¹ or higher.

The aromatic rings can be unsubstituted or substituted, e.g. by a C1 to20 alkyl group such as ethyl.

The polyaniline can be a copolymer of aniline and preferred copolymersare the copolymers of aniline with o-anisidine, m-sulphanilic acid oro-aminophenol, or o-toluidine with o-aminophenol, o-ethylaniline,o-phenylene diamine or with amino anthracenes.

Other polymers of an amino substituted aromatic compound which can beused include substituted or unsubstituted polyaminonapthalenes,polyaminoanthracenes, polyaminophenaiithrenes, etc. and polymers of anyother condensed polyaromatic compound. Polyaminoanthracenes and methodsof making them are disclosed in U.S. Pat. No. 6,153,726. The aromaticrings can be unsubstituted or substituted, e.g. by a group R as definedabove.

The polyanilines can be deposited on the first electrode by conventionalmethods, e.g. by vacuum evaporation, spin coating, chemical deposition,direct electrodeposition etc. Preferably the thickness of thepolyaniline layer is such that the layer is conductive and transparentand is preferably from 20 nm to 200 nm. The ployanilines can be doped orundoped. When they are doped they can be dissolved in a solvent anddeposited as a film, when they are undoped they are solids and can bedeposited by vacuum evaporation i.e. by sublimation.

The structural formulae of some other hole transmitting materials areshown in FIGS. 1, 2, 3, 4 and 5 of the drawings, where R, R₁, R₂ and R₃can be the same or different and are selected from hydrogen, andsubstituted and unsubstituted hydrocarbyl groups such as substituted andunsubstituted aliphatic groups, substituted and unsubstituted aromatic,heterocyclic and polycyclic ring structures, fluorocarbons such astrifluoryl methyl groups, halogens such as fluorine or thiophenylgroups; R₁, R₂ and R₃ can also form substituted and unsubstituted fusedaromatic, heterocyclic and polycyclic ring structures and can becopolymerisable with a monomer, e.g. styrene. X is Se, S or O, Y can behydrogen, substituted or unsubstituted hydrocarbyl groups, such assubstituted and unsubstituted aromatic, heterocyclic and polycyclic ringstructures, fluorine, fluorocarbons such as trifluoryl methyl groups,halogens such as fluorine or thiophenyl groups or nitrile.

Examples of R₁ and/or R₂ and/or R₃ include aliphatic, aromatic andheterocyclic alkoxy, aryloxy and carboxy groups, substituted andsubstituted phenyl, fluorophenyl, biphenyl, phenanthrene, anthracene,naphthyl and fluorene groups alkyl groups such as t-butyl, heterocyclicgroups such as carbazole.

The hole transporting material can optionally be mixed with theelectroluminescent material in a ratio of 5-95% of theelectroluminescent material to 95 to 5% of the hole transportingcompound.

Other hole transporting materials which can be used are conjugatedpolymers.

U.S. Pat. No. 5,807,627 discloses an electroluminescence device in whichthere are conjugated polymers in the electroluminescent layer. Theconjugated polymers referred to are defined as polymers for which themain chain is either fully conjugated possessing extended pi molecularorbitals along the length of the chain or else is substantiallyconjugated, but with interruptions to conjugation, either random orregular along the main chain. They can be homopolymers or copolymers.

The conjugated polymer used can be any of the conjugated polymersdisclosed or referred to in U.S. Pat. No. 5,807,627, PCT/WO90/13148 andPCT/WO92/03490.

The conjugated polymers disclosed are poly (p-phenylenevinylene)-PPV andcopolymers including PPV. Other preferred polymers are poly(2,5dialkoxyphenylene vinylene) such as poly(2-methoxy-5-(2-methoxypentyloxy-1,4-phenylene vinylene),poly(2-methoxypentyloxy)-1,4-phenylenevinylene),poly(2-methoxy-5-(2-dodecyloxy-1,4-phenylenevinylene) and other poly(2,5dialkoxyplhenylenevinylenes) with at least one of the alkoxy groupsbeing a long chain solubilising alkoxy group, poly fluorenes andoligofluorenes, polyphenylenes and oligophenylenes, polyanthracenes andoligo anthracenes, ploythiophenes and oligothiophenes.

In PPV the phenylene ring may optionally carry one or more substituents,e.g. each independently selected from alkyl, preferably methyl, alkoxy,preferably methoxy or ethoxy.

Any poly(arylenevinylene) including substituted derivatives thereof canbe used and the phenylene ring in poly(p-phenylenevinylene) may bereplaced by a fused ring system such as anthracene or naphthlyene ringand the number of vinylene groups in each polyphenylenevinylene moeitycan be increased, e.g. up to 7 or higher.

The conjugated polymers can be made by the methods disclosed in U.S.Pat. No. 5,807,627, PCT/WO90/13 148 and PCT/WO92/03490.

The hole transmitting material and the light emitting metal compound canbe mixed to form one layer, e.g. in an proportion of 5 to 95% of thehole transmitting material to 95 to 5% of the light emitting metalcompound.

Optionally there is a layer of an electron transmitting material betweenthe cathode and the electroluminescent material layer. The electrontransmitting material is a material which will transport electrons whenan electric current is passed through it. Electron transmittingmaterials include a metal complex such as a metal quinolate, e.g. analuminium quinolate, lithium quinolate, a cyano anthracene such as 9,10dicyano anthracene, a polystyrene sulphonate and compounds of formulaeshown in FIGS. 6 and 7. Instead of being a separate layer the electrontransmitting material can be mixed with the electroluminescent materialto form one layer, e.g. in a proportion of 5 to 95% of the electrontransmitting material to 95 to 5% of the light emitting metal compound.

The electroluminescent layer can comprise a mixture of the lightemitting metal compound with the hole transmitting material and electrontransmitting material.

The electroluminescent material can be deposited on the substratedirectly by vacuum evaporation or evaporation from a solution in anorganic solvent. The solvent which is used will depend on the materialbut chlorinated hydrocarbons such as dichloromethane and n-methylpyrrolidone; dimethyl sulphoxide; tetra hydrofuran; dimethylformamideetc. are suitable in many cases.

Alternatively electroluminescent material can be deposited by spincoating from solution, or by vacuum deposition from the solid state,e.g. by sputtering, or any other conventional method can be used.

Preferably the first electrode is a transparent substrate such as aconductive glass or plastic material which acts as the anode. Preferredsubstrates are conductive glasses such as indium tin oxide coated glass,but any glass which is conductive or has a transparent conductive layersuch as a metal or conductive polymer can be used.

Conductive polymers and conductive polymer coated glass or plasticsmaterials can also be used as the substrate.

The second electrode functions as the cathode and can be any low workfunction metal, e.g. aluminium, calcium, lithium, silver/magnesiumalloys etc; aluminium is a preferred metal.

The display of the invention may be monochromatic or polychromatic.Electroluminescent rare earth chelate compounds are known which willemit a range of colours, e.g. red, green, and blue light and white lightand examples are disclosed in Patent Applications WO98/58037PCT/GB98/01773, PCTVGB99/03619, PCT/GB99/04030, PCT/GB99/04024,PCT/GB99/04028, PCT/GB00/00268 and can be used to form OLEDs emittingthose colours. Thus, a full colour display can be formed by arrangingthree individual backplanes, each emitting a different primarymonochrome colour, on different sides of an optical system, from anotherside of which a combined colour image can be viewed. Alternatively, rareearth chelate electroluminescent compounds emitting different colourscan be fabricated so that adjacent diode pixels in groups of threeneighbouring pixels produce red, green and blue light. In a furtheralternative, field sequential colour filters can be fitted to a whitelight emitting display.

Either or both electrodes can be formed of silicon and theelectroluminescent material and intervening layers of a holetransporting and electron transporting materials can be formed as pixelson the silicon substrate. Preferably each pixel comprises at least onelayer of a rare earth chelate electroluminescent material and an (atleast semi-) transparent electrode in contact with the organic layer ona side thereof remote from the substrate.

Preferably, the substrate is of crystalline silicon and the surface ofthe substrate may be polished or smoothed to produce a flat surfaceprior to the deposition of electrode, or electroluminescent compound.Alternatively a non-planarised silicon substrate can be coated with alayer of conducting polymer to provide a smooth, flat surface prior todeposition of further materials.

In one embodiment, each pixel comprises a metal electrode in contactwith the substrate. Depending on the relative work functions of themetal and transparent electrodes, either may serve as the anode with theother constituting the cathode.

When the silicon substrate is the cathode an indium tin oxide coatedglass can act as the anode and light is emitted through the anode. Whenthe silicon substrate acts as the anode, the cathode can be formed of atransparent electrode which has a suitable work function, for example bya indium zinc oxide coated glass in which the indium zinc oxide has alow work function. The anode can have a transparent coating of a metalformed on it to give a suitable work function. These devices aresometimes referred to as top emitting devices or back emitting devices.

The metal electrode may consist of a plurality of metal layers, forexample a higher work function metal such as aluminium deposited on thesubstrate and a lower work function metal such as calcium deposited onthe higher work function metal. In another example, a further layer ofconducting polymer lies on top of a stable metal such as aluminium.

Preferably, the electrode also acts as a mirror behind each pixel and iseither deposited on, or sunk into, the planarised surface of thesubstrate. However, there may alternatively be a light absorbing blacklayer adjacent to the substrate.

In still another embodiment, selective regions of a bottom conductingpolymer layer are made non-conducting by exposure to a suitable aqueoussolution allowing formation of arrays of conducting pixel pads whichserve as the bottom contacts of the pixel electrodes.

As described in WO00/60669 the brightness of light emitted from eachpixel is preferably controllable in an analogue manner by adjusting thevoltage or current applied by the matrix circuitry or by inputting adigital signal which is converted to an analogue signal in each pixelcircuit. The substrate preferably also provides data drivers, dataconverters and scan drivers for processing information to address thearray of pixels so as to create images. When an electroluminescentmaterial is used which emits light of a different colour, depending onthe applied voltage, the colour of each pixel can be controlled by thematrix circuitry.

In one embodiment, each pixel is controlled by a switch comprising avoltage controlled element and a variable resistance element, both ofwhich are conveniently formed by metal-oxide-semiconductor field effecttransistors (MOSFETs) or by an active matrix transistor.

The invention is illustrated in the examples.

EXAMPLE 1 Preparation ofTris-(4-^(t)Butylacetyl-3-methyl-1-phenyl-pyrazol-5-onato)Gallium(Ga(^(t)BuPz)₃

4-^(t)Butylacetyl-3-methyl-1-phenyl-pyrazol-5-one (2.83 g. 10.39 mmol),in a 100 mI round bottom flask, was dissolved in ethanol (˜50 mL) withgentle heating. Gallium(III) chloride (0.61 g, 3.46 mmol) was dissolvedin H₂O(˜10 mL) and added to the pyrazolone solution. The resultingsuspension was heated to reflux for 2 hours and then allowed to cool.The resulting suspension was filtered and washed with H₂O (3×10 ml) andEtOH (3×10 ml) then dried under vacuum at 80° C. to give a pink powderwith the following analysis. Ga(^(t)BuPz)₃ C H N Theoretical 65.24 6.509.51 Found 65.07 6.57 9.46

-   Melting point: 252.1° C. (D.S.C.)-   Emission λ_(max).: −450 nm-   Photoluminescence Efficiency (x,y): 0.001 cdm²μW⁻¹(0.21, 0.24)    PL Measurement:

PL spectra was measured by Lot Oriel Multispec Model 77400 CCD Camera.

The measurement was carried out from the powder by spreading the powderon a spectrosil plate.

Reagents Gallium(III) chloride, anhydrous, 99.99%; Aldrich; 45,089-84-^(t)Butylac˜tyl-3-methyl-1-phenyl-pyrazol-5-onato as prepared Ethanol,denatured with 4.8% Methanol; Fluka; 02857

EXAMPLE 2 Preparation ofTris-(4-tButylacetyl-3-methyl-1-phenyl-pyrazol-5-onato)Lanthanum(La(^(t)BuPz)₃

4-^(t)Butylacetyl-3-methyl-1-phenyl-pyrazol-5-one (2.93 g, 10.76 mmol),in a 100 ml round bottom flask, was dissolved in ethanol (˜50 mL) withgentle heating. Lanthanum(III) chloride (1.27 g, 3.59 mmol) wasdissolved in H₂O(˜10 mL) and added to the pyrazolone solution. Theresulting suspension was heated to reflux for 2 hours and then allowedto cool. The resulting suspension was filtered and washed with H₂O (3×10mL) and EtOH (3×10 mL) then dried under vacuum at 80° C. to give a whitepowder with the following analysis. Sc(^(t)BuPz)₃ C H N Theoretical60.48 6.03 8.82 Found 59.92 6.28 8.67

-   Melting point: 114.1° C. (T_(g))-   Emission λmax.: 441.8 nm-   Photoluminescence Efficiency (x,y): 0.003 cdm²μW⁻¹ (0.20, 0.22)    Reagents-   Lanthanum(III) chloride hexahydrate, 99.9%; Strem Chmeicals,    93-5731; Lot no. 251194-S-   4-^(t)Butylacetyl-3-methyl-1-phenyl-pyrazol-5-one as prepared-   Ethanol, denatured with 4.8% Methanol; Fluka; 02857.

EXAMPLE 3 Preparation ofTri-(4-^(t)Butylacetyl-3-methyl-phenyl-prazol-5-onato)Scandium(Sc(^(t)BuPz)₃

4-^(t)Butylacetyl-3-methyl-1-phenyl-pyrazol-5-one (1.07 g. 3.93 mmol),in a 100 ml round bottom flask, was dissolved in ethanol (—50 mL) withgentle heating. Scandium(III) chloride hexahydrate (0.34 g. 1.31 mmol)was dissolved in H₂O(˜40 mL) and added to the pyrazololie solution. Theresulting suspension was heated to reflux for 2 hours and then allowedto cool. The resulting suspension was filtered and washed with H₂O (3×10ml,) and EtOH (3×10 ml) then dried under vacuum at 80° C. to give awhite powder with the following analysis. Sc(^(t)BuPz)₃ C H NTheoretical 67.12 6.69 9.78 Found 66.73 6.65 9.62

-   Melting point: 275.5° C. (D.S.C.)-   Emission Max.: 448.55 nm-   Photoluminescence Efficiency (x,y): 0.004 cdm²μW⁻¹ (0.22, 0.28)    Reagents-   Scandium(III) chloride hexahydrate, 99.9%; Strem Chemicals; 93-2111,    Lot no. B4745091-   4-^(t)Butylacetyl-3-methyl-1-phenyl-pyrazol-5-one as prepared-   Ethanol, denatured with 4.8% Methanol; Fluka; 02857

EXAMPLE 4 Preparation ofTris-(4-^(t)Butylacetyl-3-methyl-1-phenyl-pyrazol-5-onato)Terbium(Tb(^(t)BuPz)₃

4-^(t)Butylacetyl-3-methyl-1-phenyl-pyrazol-5-one (1.45 g, 5.32 mmol),in a 100 ml round bottom flask, was dissolved in ethanol (˜50 mL) withgentle heating. Terbium(III) chloride hexahydrate (0.66 g, 1.77 mmol)was dissolved in H₂O(˜10 mL) and added to the pyrazolone solution. Theresulting suspension was heated to reflux for 2 hours and then allowedto cool. The resulting suspension was filtered and washed with H₂O (3×10mL) and EtOH (3×10 mL) then dried under vacuum at 80° C. to give a whitepowder with the following analysis. Tb(^(t)BuPz)₃ C H N Theoretical59.24 5.91 8.64 Found 59.86 6.23 8.75

-   Melting point: 252.6° C. (D.S.C.)-   Emission Max.: 492.4 nm, 547.6 nm-   Photoluminescence Efficiency (x,y): cdm²μW⁻¹

Reagents

-   Terbium(III) chloride, 99.9%; Acros-   4-^(t)Butylacetyl-3-methyl-1-phenyl-pyrazol-5-one as prepared-   Ethanol, denatured with 4.8% Methanol; Fluka; 02857

EXAMPLE 5 Preparation ofTetrakis-(4-^(t)Butylacetyl-3-methyl-1-phenyl-pyrazol-5-onato)Thorium(Th(^(t)BuPz)₃

4-^(t)Butylacetyl-3-methyl-1-phenyl-pyrazol-5-one (1.92 g. 7.06 mmol),in a 100 ml round bottom flask, was dissolved in ethanol (˜50 mL) withgentle heating. Thorium(IV) chloride hexahydrate (0.66 g. 1.77 mmol) wasdissolved in H₂O(˜10 mL) and added to the pyrazolone solution. Theresulting suspension was heated to reflux for 2 hours and then allowedto cool. The resulting suspension was filtered and washed with H₂O (3×10ml) and EtOH (3×10 mL) then dried under vacuum at 80° C. to give a pinkpowder with the following analysis. Th(^(t)BuPz)₄ C H N Theoretical58.35 5.81 8.58 Found 58.49 6.06 8.32

-   Melting point: 254.7° C. (D.S.C.)-   Emission Max.: 462.8 nm-   Photoluminescence Efficiency (x,y): 0.002 cdm²μW⁻¹ (0.27, 0.36)    Reagents-   Thorium(IV) chloride hydrate, 99.9%; Strem Chemicals; 09-3155-   4-^(t)Butylacetyl-3-methyl-1-phenyl-pyrazol-5-one; as prepared-   Ethanol, denatured with 4.8% Methanol; Fluka; 02857

EXAMPLE 6Tris-(4-^(t)Butylacetyl-3-methyl-1-phenyl-pyrazol-5-onato)Calcium(Ca(^(t)BuPz)₂

(Ca(^(t)BuPz)₂was prepared by the method of Example using calciumchloride in place of the Terbium chloride.

EXAMPLE 7

The (Tb(^(t)BuPz)₃ of Example 4 was heated at reflux withdiphenylphosphinic-azide in trimethyl pentane and the mixture heated toreflux until a clear solution was obtained (about 1 hour). The solutionwas allowed to clear yielding (Tb(^(t)BuPz)₃)diphenylphosponimidetris-phenylphosphorane,(Tb(^(t)BuPz)₃OPNP[Tb(pyr)₃OPNP] as a crystalline solid.

EXAMPLE 8

The (Ca₂(^(t)BuPz)₃ of Example 6 was heated under reflux withphenanthrene in chloroform overnight. The solvent was removed in vacuoto yield a solid which was (Ca₂(^(t)BuPz)₃Phen₂[Ca(pyr)₂Phen₂]

Device Fabrication

An indium tin oxide (ITO) coated glass piece (1×1 cm² ) had a portionetched out with concentrated hydrochloric acid to remove the ITO and wascleaned and dried. Four devices were fabricated

Device 1 was fabricated by sequentially forming on the ITO, layerscomprising ITO/α-NPB(75 nm)/Tb(pyr)₃OPNP(50 nm)/BCP(20 nm)Alq₃(40nm)LiF(0.5 nm/Al where α-NPB is in FIG. 1, BCP is bathocupron, LiF islithium fluoride and Alq₃ is aluminium quinolate.

Device 2 was fabricated by sequentially forming on the ITO, layerscomprising ITO/α-NPB(10 nm)/Tb(pyr)₃OPNP(50 nm)/BCP(20 nm)Alq₃(40nm)LiF(0.7 nm/Al

Device 3 was fabricated by sequentially forming on the ITO, layerscomprising ITO(100 Ωsqr)/CuPc(8 nm)/α-NPB(60 nm)/Ca(pyr)₂Phen₂(50nm)/Alq₃(10 nm)/LiF(0.7 nm)/Al where CuPc is copper phthalocyanine,

Device 4 was fabricated by sequentially forming on the ITO, layerscomprising ITO(100 Ωsqr)/CuPc(8 nm)α-NPB(60 nm)/Ca(pyr)₂Phen₂(10 nm)/Al

The organic coating on the portion which had been etched with, theconcentrated hydrochloric acid was wiped with a cotton bud. The coatedelectrodes were stored in a vacuum desiccator over a molecular sieve andphosphorous pentoxide until they were loaded into a vacuum coater(Edwards, 10⁻⁶ torr) and aluminium top contacts made. The active area ofthe LED's was 0.08 cm2 by 0.1 cm² the devices were then kept in a vacuumdesiccator until the electroluminescence studies were performed.

The ITO electrode was always connected to the positive terminal. Thecurrent vs. voltage studies were carried out on a computer controlledKeithly 2400 source meter. Electroluminescence spectra were recorded bymeans of a computer controlled charge coupled device on PR650 systemmade by Photoresearch Inc.

The results are shown in FIGS. 16 to 23.

1-23. (canceled)
 24. An electroluminescent compound which has thegeneral chemical formula

wherein M is a metal other than aluminum; n is the valency of M; R₁, R₂and R₃, which may be the same or different, are selected from the groupconsisting of hydrogen, hydrocarbyl groups, substituted andunsubstituted aliphatic groups, substituted and unsubstituted aromatic,heterocyclic and polycyclic ring structures, fluorocarbon groups,halogen groups, thiophenyl groups, and nitrile groups; or alternativelyR₁ and R₃ can form ring structures, or any of R₁, R₂ and R₃ can becopolymerized with a monomer.
 25. A compound according to claim 24wherein M is selected from the group consisting of gallium, indium,germanium, tin (II), tin (IV), antimony (II), antimony (IV), lead (II),lead (IV), metals of the first, second and third groups of transitionmetals in any valence states, manganese, iron, ruthenium, osmium,cobalt, nickel, palladium(II), palladium(IV), platinum(II),platinum(IV), cadmium, chromium. titanium, vanadium, zirconium,tantulum, molybdenum, rhodium, iridium, niobium, scandium and yttrium.26. An electroluminescent compound which has the general chemicalformula

wherein Lα has the general chemical formula

M is a metal, n is the valency of M, Lp is a neutral ligand, and R₁, R₂and R₃, which may be the same or different, are selected from the groupconsisting of hydrogen, hydrocarbyl groups, substituted andunsubstituted aliphatic groups, substituted and unsubstituted aromatic,heterocyclic and polycyclic ring structures, fluorocarbon groups,halogen groups, thiophenyl groups, and nitrile groups; or alternativelyR₁ and R₃ can form ring structures, or any of R₁, R₂ and R₃ can becopolymerized with a monomer.
 27. An electroluminescent compoundaccording to claim 26 wherein the groups L_(p) are selected fromcompounds having the general chemical formula

wherein each Ph which can be the same or different and is selected fromthe group consisting of phenyl (OPNP) and substituted phenyl groups,other substituted or unsubstituted aromatic groups, substituted orunsubstituted heterocyclic or polycyclic groups, substituted orunsubstituted fused aromatic groups, naphthyl groups, anthracene groups,phenanthrene groups, and pyrene groups, and the substituents insubstituted phenyl groups are selected from the group consisting ofalkyl groups, aralkyl groups, alkoxy groups, aromatic groups,heterocyclic groups, polycyclic groups, halogen groups, cyano groups,amino groups groups having any of the following general chemicalformulas:

wherein R₁, R₂ and R₃ are as previously defined; groups having any ofthe following general chemical formulas:

wherein R₁, R₂ and R₃ are as previously defined; and groups having anyof the following general chemical formulas:

wherein Ph is as previously defined.
 28. An electroluminescent compoundaccording to claim 26 wherein M is a metal selected from the groupconsisting of gallium, indium, aluminum, germanium, tin (II), tin (IV),antimony (II), antimony (V), lead (II), lead (IV) and metals of thefirst, second and third groups of transition metals in different valencestates e.g. manganese, iron, ruthenium, osmium, cobalt, nickel,palladium(II), palladium(IV), platinum(II), platinum(IV), cadmium,chromium, titanium, vanadium, zirconium, tantulum, molybdenum, rhodium,iridium, niobium, scandium or yttrium.
 29. An electroluminescent devicecomprising: (i) a first electrode; (ii) an electroluminescent layerconsisting essentially of a layer of an electroluminescent complexaccording to claim 24 of the general chemical formula

wherein M, n, R₁, R₂ and R₃ are as previously defined; and (iii) asecond electrode.
 30. An electroluminescent device according to claim 29wherein M is selected from the group consisting of gallium, indium,germanium, tin (II), tin (IV), antimony (II), antimony (IV), lead (II),lead (IV), metals of the first, second and third groups of transitionmetals in any valence states, manganese, iron, ruthenium, osmium,cobalt, nickel, palladium(II), palladium(IV), platinum(II),platinum(IV), cadmium, chromium. titanium, vanadium, zirconium,tantulum, molybdenum, rhodium, iridium, niobium, scandium, and yttrium;and further wherein R₃ is a phenyl or substituted phenyl group.
 31. Anelectroluminescent device comprising: (i) a first electrode; (ii) anelectroluminescent layer consisting essentially of a layer of anelectroluminescent compound according to claim 26 of the generalchemical formula

wherein Lα, M, n and Lp are as previously defined; and (iii) a secondelectrode.
 32. An electroluminescent device according to claim 31wherein M is a metal selected from gallium, indium, aluminum, germanium,tin (II), tin (IV), antimony (II), antimony (IV), lead (II), lead (IV)and metals of the first, second and third groups of transition metals indifferent valence states e.g. manganese, iron, ruthenium, osmium,cobalt, nickel, palladium(II), palladium(IV), platinum(II),platinum(IV), cadmium, chromium, titanium, vanadium, zirconium,tantulum, molybdenum, rhodium, iridium, niobium, scandium or yttrium.33. An electroluminescent device according to claim 31 wherein thegroups L_(p) are selected from compounds having the general chemicalformula

wherein each Ph which can be the same or different and is selected fromthe group consisting of phenyl (OPNP) and substituted phenyl groups,other substituted or unsubstituted aromatic groups, substituted orunsubstituted heterocyclic or polycyclic groups, substituted orunsubstituted fused aromatic groups, naphthyl groups, anthracene groups,phenanthrene groups, and pyrene groups, and the substituents insubstituted phenyl groups are selected from the group consisting ofalkyl groups, aralkyl groups, alkoxy groups, aromatic groups,heterocyclic groups, polycyclic groups, halogen groups, cyano groups,amino groups, groups having any of the following general chemicalformulas:

wherein R₁, R₂ and R₃ are as previously defined; groups having any ofthe following general chemical formulas:

wherein R₁, R₂ and R₃ are as previously defined; and groups having anyof the following general chemical formulas:

wherein Ph is as previously defined.
 34. An electroluminescent deviceaccording to claim 29 wherein there is a layer of a hole transmittingmaterial between the first electrode and the layer of theelectroluminescent complex.
 35. An electroluminescent device accordingto claim 34 wherein the hole transmitting material is selected from thegroup consisting of aromatic amine complexes and conjugated polymers.36. An electroluminescent device according to claim 34 wherein the holetransmitting material is a film of a polymer selected from the groupconsisting of poly(vinylcarbazole); N,N′-diphenyl-N,N′-bis(3-methylphenyl)-1,1′-biphenyl-4,4′-diamine (TPD); polyaniline;substituted polyanilines; polythiophenes; substituted polythiophenes;polysilanes and substituted polysilanes; polymers of cyclic aromaticcompounds; poly (p-phenylenevinylene)-PPV and copolymers; PPV; poly(2,5dialkoxyphenylene vinylene); poly(2-methoxy-5-(2-methoxypentyloxy-1,4-phenylene vinylene);poly(2-methoxypentyloxy)-1,4 phenylenevinylene);poly(2-methoxy-5-(2-dodecyloxy-1,4-phenylenevinylene); other poly(2,5dialkoxyphenylenevinylenes) with at least one of the alkoxy groups beinga long chain solubilising alkoxy group; poly fluorenes; oligofluorenes;polyphenylenes; oligophenylenes; polyanthracenes and oligo anthracenes;and polythiophenes and oligothiophenes.
 37. An electroluminescent deviceaccording to claim 31 wherein there is a layer of a hole transmittingmaterial between the first electrode and the layer of electroluminescentcompound, and further wherein the hole transmitting material is selectedfrom the group consisting of aromatic amine complexes and conjugatedpolymers.
 38. An electroluminescent device according to claim 37 whereinthe hole transmitting material is a film of a polymer selected from thegroup consisting of poly(vinylcarbazole);N,N′-diphenyl-N,N′-bis(3-methylphenyl)-1,1′-biphenyl-4,4′-diamine (TPD);polyaniline; substituted polyanilines; polythiophenes; substitutedpolythiophenes; polysilanes and substituted polysilanes; polymers ofcyclic aromatic compounds, poly(p-phenylenevinylene)-PPV and copolymers;PPV; poly(2,5 dialkoxyphenylene vinylene);poly(2-methoxy-5-(2-methoxypentyloxy-1,4-phenylene vinylene);poly(2-methoxypentyloxy)-1,4-phenylenevinylene);poly(2-methoxy-5-(2-dodecyloxy-1,4-phenylenevinylene); other poly(2,5dialkoxyphenylenevinylenes) with at least one of the alkoxy groups beinga long chain solubilising alkoxy group; poly fluorenes; oligofluorenes;polyphenylenes; oligophenylenes; polyanthracenes and oligo anthracenes;polythiophenes and oligothiophenes.
 39. An electroluminescent deviceaccording to claim 29 wherein there is a layer of an electrontransmitting material between the electroluminescent compound layer andthe second electrode.
 40. An electroluminescent device according toclaim 39 wherein the electron transmitting material is selected from thegroup consisting of metal quinolates and cyano anthracenes.
 41. Anelectroluminescent device according to claim 39 wherein the electrontransmitting material is an aluminum quinolate or lithium quinolate. 42.An electroluminescent device according to claim 31 wherein there is alayer of an electron transmitting material between theelectroluminescent compound layer and the second electrode.
 43. Anelectroluminescent device according to claim 42 wherein the electrontransmitting material is selected from the group consisting of metalquinolates and cyano anthracenes.
 44. An electroluminescent deviceaccording to claim 42 wherein the electron transmitting material is analuminum quinolate or lithium quinolate.
 45. An electroluminescentdevice according to claim 29 wherein the second electrode is a materialselected from the group consisting of aluminum, calcium, lithium, andsilver/magnesium alloys.
 46. An electroluminescent device according toclaim 31 wherein the second electrode is a material selected from thegroup consisting of aluminum, calcium, lithium, and silver/magnesiumalloys.
 47. An electroluminescent device according to claim 34 whereinthe hole transmitting material and the electroluminescent compound aremixed to form one layer in a proportion ranging from about 5% of theelectroluminescent compound and 95% of the hole transmitting material toabout 95% of the electroluminescent compound and 5% of the holetransmitting material.
 48. An electroluminescent device according toclaim 39 wherein the electron transmitting material and the lightemitting metal compound are mixed to form one layer in a proportionranging from about 5% of the light emitting metal compound and 95% ofthe electron transmitting material to about 95% of the light emittingmetal compound and 5% of the electroluminescent compound.
 49. Anelectroluminescent device according to claim 48 wherein there is acopper phthalocyanine layer on the first electrode and a lithiumfluoride layer on the second electrode.